1. Field of Invention
The present invention relates to a system for providing to the location of a telephone apparatus both telephone signals and electric power by way of a single ordinary multi-conductor telephone installation cable.
2. Elements of Prior Art
At many locations where a telephone apparatus is installed, such as at certain telephone booths, electric power is required to provide for desired functions ancillary to the use of the telephone apparatus. A typical such ancillary function is lighting suitable to permit convenient use of the telephone apparatus and of a telephone directory.
In such cases, the telephone signals are transmitted by way of an ordinary multi-conductor telephone installation cable, and ordinary 120 Volt/60 Hz electric power is transmitted by way of a different and completely separate cable.
In view of the National Electrical Code and the requirements of Underwriters Laboratories Inc. (U.L.), it would not be permissible to transmit the ordinary 120 Volt/60 Hz power line voltage along with the telephone signals in an ordinary multi-conductor telephone installation cable.